Patients with chronic myeloid leukemia (CML) who receive half the standard dose of tyrosine kinase inhibitor (TKI) therapy are likely to eliminate most adverse events, drastically reduce costs, and improve relapse-free survival rates, according to research presented at the 22nd Congress of the European Hematology Association (June 22-25, 2017; Madrid, Spain).
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Targeted therapy with TKIs has significantly improved survival outcomes for patients with CML. However, lifelong daily treatment increases the risk of heightened adverse events and a profoundly high cost. Recent studies have examined the feasibility of stopping TKI therapy in those patients who have achieved a sustained deep molecular response of MR4 or better.
Richard E Clark, MD, professor of hematology, department of molecular and clinical cancer medicine, University of Liverpool (England), and colleagues conducted a study to examine the effects of TKI de-escalation as a precursor to complete cessation in patients with stable major molecular response (MMR) or MR4 or greater. Researchers enrolled 174 patients (MMR cohort, n = 49; MR4 cohort, n = 125) with CML who received TKI therapy for three years or longer and exhibited molecular response for 12 months or longer. Participants received half their standard TKI dose (imatinib 200 mg daily, dasatinib 50 mg daily, or nilotinib 200 mg twice daily) for 12 additional months.
Results of the study indicated that a 12-month period of reduced TKI dosage prior to complete cessation correlated to a 20% improvement in relapse-free survival rates compared with complete cessation without de-escalation.
“We never thought for a minute that we would get better results in ultimately stopping just by having an extra year of de-escalation,” said Dr Clark in his presentation.
Along with improving relapse-free survival rates, TKI de-escalation reportedly improved adverse events, such as lethargy, diarrhea, rash, and nausea.
From a cost perspective, the average cost of TKI treatment for uninsured patients with CML in the United States is approximately $146,000. Reducing or ending treatment, researchers reported, would yield billions in cancer cost savings.
Further studies of more aggressive TKI de-escalation are warranted, researchers concluded.—Zachary Bessette
